The present invention relates to a vehicle seat, in particular for a truck, having at least one structurally fixed part and at least one adjustable part which is movable relative to the structurally fixed part.
A known vehicle seat of this type has a seat frame which can be adjusted vertically by means of a scissors-type substructure and an electric motor mounted thereon.
It is an object of the present invention to provide an improved vehicle seat of the type mentioned at the beginning.
In accordance with one aspect of the present invention, an adjustable vehicle seat comprises a structurally fixed part, at least one adjustable part mounted for moving relative to the structurally fixed part, and an inflatable cushion positioned between the adjustable part and the structurally fixed part. The inflatable cushion is operative for pneumatically adjusting the position of the adjustable part relative to the structurally fixed part.
In the case of trucks, including coaches, the pneumatic adjustment of parts of the vehicle seat has the advantage that the compressed air supply which is already available can be shared, making additional electric motors for adjustment purposes unnecessary. This simplifies and reduces the cost of the production of the vehicle seat. The inflatable cushion between the adjustable part and the structurally fixed part means that the pneumatic adjustment can take place with few components and in a simple manner. A vehicle seat of this type can be produced with little outlay on material and in terms of time and is thereby cost effective.
In one preferred embodiment, adjustable side pieces are provided which are coupled to a backrest frame of the vehicle seat and can be adjusted in their pivoting angle with respect to the backrest frame. In order to arrange the inflatable cushion in such a manner that it does not interfere with the seat user, the side pieces preferably have angular elements which are, for example, formed integrally with the side pieces or are welded onto the latter, and which reach as far as the rear side of the structurally fixed part. In accordance with one aspect of this embodiment, the structurally fixed part is a lordosis support that is connected to the backrest frame. At least one tension spring is preferably provided between the angular elements on the rear side of the structurally fixed part, which tension spring attempts to position the angular elements against the rear side of the structurally fixed part. A respective inflatable cushion is preferably provided between each angular element and the rear side of the structurally fixed part, which cushion attempts to push the relevant angular element away from the rear side of the structurally fixed part counter to the force of the tension spring. Two cushions have the advantage over one cushion in that no unintentional changing of the adjustment takes place due to a side piece being stressed on one side when cornering. In the case of a single cushion, the cushion would assume an asymmetrical form due to the air flowing from one half into the other. In order to protect the cushions, and as the stop for the angular elements, a covering is preferably provided on that side of the angular elements which faces away rearward from the rear side of the structurally fixed part.
In another preferred embodiment, the vehicle seat has a structurally fixed seat-shell rear part and a seat-shell front part which can be adjusted pneumatically in its inclination. A seat cushion which is fastened or rests on the seat-shell front part and on the seat-shell rear part defines the seat surface. For a thigh support, it is sufficient if only the seat-shell front part is adjustable. Greater seat comfort can be achieved by adjusting the seat-surface length. More specifically, the seat-shell front part can be displaced relative to the seat-shell rear part, for example by the seat-shell front part being guided on a carrier plate coupled to a structurally fixed seat frame. As a result, and for example, a multi-adjustable vehicle seat is provided with few components. For reliable guiding during the seat-surface length adjustment, slideways are provided on the seat-shell front part and/or on the carrier plate. The seat-shell front part is preferably locked by means of a locking bar which is mounted movably on the carrier plate, is movable relative to the seat-shell front part and, for locking purposes, interacts with a toothed segment of the seat-shell front part. This makes reliable locking and easy unlocking possible. For better performance during a crash, it is advantageous if the locking bar is movable transversely to the seat longitudinal direction. In order to enable adjustment in a gap-free manner in the various seat-surface lengths, the seat cushion reaches, for example, a small distance below the backrest.